Long Press Button issue on moving mouse - unity3d

Question

I use a long press button, which works very well, on MouseDown and if I don't move the mouse, at the end of my delay, I have my action.
If I move the mouse (still pressing down and still on the button) it resets my button's delay, and I don't understand why.
if anyone has an idea, it would help me a lot.
Thx
Here's my code :
private bool _PointerDown;
public float DelaiReponse;
private float _PointerDownTimer;
private bool _IsValidate = false;
private float _Delai;
public void OnPointerDown(PointerEventData eventData)
{
_PointerDown = true;
}
public void OnPointerUp(PointerEventData eventData)
{
_PointerDown = false;
_PointerDownTimer = 0;
}
void Start()
{
_Delai = DelaiReponse;
}
private void Update()
{
if (_PointerDown) // Timer Button Validation Hold
{
_PointerDownTimer += Time.deltaTime;
if (_PointerDownTimer >= _Delai)
{
_IsValidate = true;
}
}
}enter code here

Answer 1

Using Input.GetMouseDown(0) and Input.GetMouseButtonUp(0) could fix the problem:
private void Update()
{
if (Input.GetMouseDown(0))
{
_PointerDown = true;
}
if (Input.GetMouseUp(0))
{
_PointerDown = false;
_PointerDownTimer = 0;
}
if (_PointerDown) // Timer Button Validation Hold
{
:
:
}
:
:
}

Answer 2

I finally found
OnMouseDown even worked outside my button, and I preferred the OnPointerDown method.
I added IDragHandler to my class, and create a bool _PointerDrag
private bool _PointerDown;
private bool _PointerDrag;
public float DelaiReponse;
private float _PointerDownTimer;
private bool _IsValidate = false;
private float _Delai;
public class LongClickButton : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IDragHandler
{
public void OnPointerDown(PointerEventData eventData)
{
_PointerDown = true;
}
public void OnPointerUp(PointerEventData eventData)
{
_PointerDown = false;
_PointerDownTimer = 0;
}
public void OnDrag(PointerEventData eventData)
{
_PointerDrag = true;
}
void Start()
{
_Delai = DelaiReponse;
}
private void Update()
{
if (_PointerDown || _PointerDrag) // Timer Button Validation Hold
{
_PointerDownTimer += Time.deltaTime;
if (_PointerDownTimer >= _Delai)
{
_IsValidate = true;
}
}
}
}
and it works.
Thanks for your time, Frenchy